A PDP is a light emitting device for displaying image by exciting phosphor in a discharged cell to display image. The PDP is lighter and simpler in a fabrication process than a conventional CRT (Cathode Ray Tube), and enables a PDP monitor to be slimmer and a screen to be wider. As a result, the PDP has been frequently used for a situation board of stock exchange, a display device for a video conference and a wide screen for wall TV.
As shown in FIG. 1, in the conventional PDP, a front panel 10 is combined with a rear panel 20, and an image is displayed toward the front panel 10.
On the front panel 10, a sustain electrode X and a scan electrode Y are formed in parallel, and the sustain electrode X and the scan electrode Y comprise transparent electrodes Xa and Ya (or ITO electrodes) formed of an ITO material and bus electrodes Xb and Yb formed of an metal material.
The sustain electrode X and the scan electrode Y are covered with a dielectric film 12 for insulating both electrodes and restricting discharge current. A protective film 13 is formed on the dielectric film 12.
On the rear panel 20, barrier ribs 21 having a stripe type (or dot type) are formed in parallel. A discharge space, that is a cell C, is formed between the barrier ribs 21. An address electrode A is formed under the cell C, and covered with the dielectric film 23. A fluorescent film 24 is covered on a sidewall and a bottom of the cell C to represent red, green or blue.
If the cell C is discharged, visible rays of a corresponding color are emitted.
Although the PDP having the above-described structure has been developed to have a size of 63 inch, the embodiment of a wider screen is required.
In order to solve this problem, a multi-screen using the PDP may be provided as shown in FIG. 2. The multi-screen of FIG. 2 is formed by combining four PDPs (D1, D2, D3 and D4) to form a wide screen.
As shown in FIG. 2, each PDP used in configuration of the multi-screen has two surfaces to be adjacent to different PDPs. As a result, withdrawal directions of each electrode are limited. Thus, the sustain electrode X and the scan electrode Y are withdrawn in parallel toward the same direction, and the address electrode A is withdrawn perpendicular to the above electrodes X and Y.
Since the sustain electrode X and the scan electrode Y are withdrawn toward a peripheral portion of the PDP, a sustain signal and a scan signal are required to be applied from the same peripheral portion. However, the waveforms of the signals are more distorted as cells are farther from the peripheral portion of the PDP.
As shown in FIG. 3, pulses applied to an electrode pad are more distorted as they are transmitted into regions {circle around (1)}, {circle around (2)}, {circle around (3)}, {circle around (4)} and {circle around (5)}. As a result, a pulse type transmitted from the region {circle around (1)} has a large difference from that of the region {circle around (5)}.
As described above, since the conventional PDP has more distorted waveforms of the pulses as the pulses are transmitted farther from application locations, discharge voltage conditions are differentiated depending on the positions of the PDP.
The PDP has a larger resistance as a region is farther from an electrode pad. As a result, in the scan signal and the sustain signal, a difference in signal loss is generated by the resistance, thereby differentiating the brightness in each region. That is, as a region is farther from the electrode pad, the brightness becomes lower.
Specifically, as a measurement result of the brightness in positions P1, P2 and P3 of FIG. 3, the position P1 shows the brightness of 210 Cd/m3, the position P2 shows the brightness of 190 Cd/m3 and the position P3 shows the brightness of 160 Cd/m3.